Valve pins are well known in the art for use in controlling the flow of a molten material (melt) in an injection molding hot runner mold towards a mold cavity through a mold gate into a mold cavity. The valve pins are often controlled by an actuator, which advances or retracts the valve pin, either to vary the flow to a mold cavity or to open or close the mold gate.
In a multi-cavity mold, a plurality of valve pins are, in some instances, controlled using a common actuator, which advances and retracts the valve pins simultaneously. Due to differences in the molding conditions and machining tolerances at each mold cavity, however, it can occur that a valve pin for a particular cavity requires an adjustment so that it will properly seat in the mold gate to prevent plastic from leaking when the valve pin is moved to shut off the flow from the melt channel leading from the nozzle into the mold cavity. The ability to adjust the valve pin position for each individual nozzle is particularly useful when the pins are commonly actuated. To adjust a valve pin, an operator is typically required to remove the valve pin assembly, machine the valve pin to adjust the length, and re-insert the valve pin assembly into the machine. If the pin is the incorrect length, the procedure must be repeated again. This procedure is cumbersome, time consuming, and results in lost production time for the manufacturer.
Alternatively, the operator can insert one or more spacers to adjust the position or the length of the valve pin. While inserting spacers is easier than machining the valve pin, it is inaccurate, in that the fineness of the adjustment is limited to the thinness of the spacer.
There is a need for a device and method that permits fast, and accurate adjustment of valve pins.